The glymphatic system, the brain’s waste clearance mechanism, operates primarily during slow-wave sleep. Beta-amyloid associated with Alzheimer’s disease is cleared by this system. Sleep deprivation reduces clearance, allowing accumulation. A single night of poor sleep measurably increases beta-amyloid load.
Sleep architecture changes with age and deep slow-wave sleep decreases. Addressing sleep hygiene, sleep apnoea which is more common in older adults, and medications that disrupt sleep quality becomes more important with age. Treating sleep apnoea has shown improvement in cognitive function in older adults.